Seal-it® 540 BACKER ROD FOAM

Seal-it® 540 BACKER ROD FOAM is an open-cell, CFC-free, polyurethane-based backer rod foam, available in a range of diameters, for filling deep joints to achieve proper joint dimensioning and width/depth ratio. Also prevents three-sided adhesion in joints.



  • For achieving the optimal joint depth/width ratio, for proper joint dimensioning.
  • To prevent three-sided adhesion in dilation joints.
  • PU open-cell backer rod foam (polyurethane) is used for non-load-bearing joints.
  • PE closed-cell backer rod foam (polyethylene) provides additional support to the sealant and is therefore better suited for joints under mechanical loads or water pressure.


  • CFC-free.
  • No bubble formation when using PU open-cell backer rod foam.
  • Risk of bubble formation when using PE closed-cell backer rod foam.
  • PE closed-cell backer rod foam is 100% airtight.
  • High specific weight, heavy A- quality.
  • Lasting resistance to ageing; does not rot.
  • Easy to compress and install.
  • Compatible with all surfaces and sealants.

Application conditions

  • The diameter of Seal-it® 540 backer rod foam must be between 30% and 50% greater than the width of the joint being sealed. This ensures secure installation of the backer rod foam in the joint and prevents sagging during sealant application.
  • Do not stretch backer rod foam during application.
  • Connect the backer rods together with a bit of overlap.
  • For joints under mechanical loads or water pressure, use PE closed backer rod foam, as this provides additional support for the sealant. If using PE closed-cell backer rod foam, air may become trapped between the sealant and backing during application, which, in combination with direct sunlight, may result in bubble formation in the joint seal. Use of PU closed-cel backer rod foam does not run this risk.

Standard product line


Article number

Ø 10mm (500 metres)


Ø 15mm (250 metres)


Ø 20mm (200 metres)


Ø 25mm (100 metres)


Ø 30mm (100 metres)


Ø 35mm (50 metres)


Ø 40mm (50 metres)


Ø 50mm (50 metres)


Ø 60mm (25 metres)


Ø 70mm (25 metres)


Ø 100mm (15 metres)


SI-XXX-XXXX-XXX = Article number.
Other colours and/or packaging on request.


Technical support department

Connect Products has a state-of-the-art R&D laboratory, where experienced specialists continuously research and develop sealants, adhesives and PU foams. Customers and clients can have products researched, tested and developed by this department. You can also contact us for technical advice, tips, project support, warranty certificates, requests and other technical questions. We will be happy to assist you with high-quality technology.

Call us on +31 (0)183 731 400 or send us an e-mail.

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